This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. The purpose of this collaboration is to develop the means to image live cells with micron resolution by means of ESR microscopy. This can provide the distribution of intra or extra cellular oxygen levels as a means to provide better understanding of cell metabolism and to aid in medical diagnostics. It would also be possible to study cell migration in the blood or interstitial fluid, which is important in various physiological environments. The use of specially modified trityls which can enter the cell will be important for this study.